1. Field of the Invention
This invention relates to an alkali development type photocurable conductive paste composition for forming a fine electrode circuit on a substrate to be used in a plasma display panel (hereinafter referred to briefly as "PDP") and the PDP having electrodes thereof formed of the composition.
2. Description of the Prior Art
The PDP is a planar display for displaying images and information by virtue of the emission of light by gas discharge. By the construction of panel and the method of operation, it is known in two types, i.e. DC (direct current) type and AC (alternating current) type.
By way of example, the principle of the DC type color PDP will be briefly explained below with reference to the attached FIGURE. In the DC type color PDP, the space intervening between two transparent substrates 1a and 1b (generally glass plates) is divided into numerous minute cells by latticed barrier ribs 2 interposed between the transparent substrates. The individual cells have such a discharge gas as He or Xe sealed therein. The reference numerals 3a through 3c denote fluorescent membranes which, on being excited by the ultraviolet light generated by the discharge of the discharge gas, emits visible light of three primary colors. On the inner faces of the two substrates, electrodes 4a and 4b are disposed as opposed to each other across the relevant cells. Generally, the cathodes 4a are formed of a film of transparent electroconductive material such as NESA glass. When a high voltage is applied between these electrodes 4a and 4b, the discharge gas which is sealed in the cells induces plasma discharge P and, by virtue of the ultraviolet light radiated consequently, incites the fluorescent elements of red (3a), blue (3b), and green (3c) colors to emit lights and effect the display of an image. In the full-color display system, three fluorescent elements severally of the three primary colors of red, blue, and green mentioned above jointly form one picture element.
The cells in the DC type PDP are divided by the component barrier ribs of a lattice, whereas those in the AC type PDP are divided by the barrier ribs which are arranged parallel to each other on the faces of substrates. In either case, the cells are divided by barrier ribs. These barrier ribs are intended to confine the luminous discharge within a fixed area so as to preclude false discharge or cross talk between adjacent discharge cells and ensure ideal display.
Heretofore, in the formation of electrode circuits on the substrates of the PDP, the practice of patterning an electrode material by the use of the screen printing technique has been adopted popularly.
In fulfilling the requirements such as enlarging a screen and improving the fineness of an electrode circuit which are expected of the PDP, the conventional screen printing method necessitates skillfulness on the part of the operator, produces such blemishes as blurs or blots during the course of printing, encounters difficulty in ensuring accuracy of registration of images owing to elongation or contraction of the screen, and suffers the problem of low yield.
Incidently, photosensitive conductive pastes intended for ceramics-core printed circuit boards in which the formation of conductive patterns is effected on ceramic substrates by the technique of photolithography are under development recently.
This technique, however, is unfit for the PDP because it inherently carries out a calcining step at a temperature exceeding 800.degree. C. and, when calcined at a temperature not higher than 600.degree. C., i.e. the calcining temperature which is used during the manufacture of PDP (the substrates for the PDP must be calcined at a temperature not higher than 600.degree. C. because soda-lime glass is generally used for the substrate), inevitably produces an uncalcined residue and brings about such an effect as induces degradation of the conductivity of an electrode circuit to be formed.